Method of forming sponge substitutes.



ing a sponge substitute; starts main'object YUN'ITED STATES rt-1am"rows;

ALEXANDER-STRAUS, on EW Years, *N. Y}

METHOD"OF'JF'O'RMIN'GSPONGE SUBSTITUTYESQ SPECIFICATION formingpartot' Letters Patent Ne. 702,162, dated June to, 1902,

Application filed November 5, 1901. Serial No. 81,258. (No specimens.) F

To all whom it may concern:

Be it knownthatl; ALEXANDER STRAUS, a citizen of the United States, residing at New York, in the county andState of New York," "have invented new'and "useful Improvements in Methods of Forming Sponge'Substitutes, of which the following is a specification.

, This invention relatesto a method of formis to produce a substitute for sponge that is "elastic and absorbent and has all theother properties of'a natur'al'sponge'thatare commercially desirable.

The present process of forming a rubber sponge is in the nature of an improvement on that described and claimed in a prior appli cation filed by me September 3, 1901', Serial No. 74,081, in which I have described "a method of forming a rubber sponge by using a chemically-acting blowing ingredient, such as bicarbonate of soda, for forming the small cells and a-mechanically-acting cell-forming material, such as crushed rock salt,'for form- V ing large cells, the rubber compound with which these substances are incorporated being then subjected toheat to'form the small cells'by chemical action and also to vulcanize the rubber, after which the 'lumps'of rock salt are dissolved out, as'by means of hot water. I have found that a'sponge substitute or rubber sponge may-be perfectly formed in a simpler manner withoutthe use of any me- 7 I chanically-acting particles for molding large poratingwithrubber, preferably the usual cells, and inthe present case both the large and the-small cells may be formedby incorrubber compound or sulfurized rubber, a sufficient quantity of a chemically-acting cellforming solvent of rubber to 'partially'dise solve the rubber and distend the mass before l1eating,this substance being also capable of reacting chemically upon the constituent ele- .ments of the-sulfurized rubber to generate the rubber and causing the remainder to be distended as a result of the'capillary absorption of the hydrocarbon incorporated with the rubber. Various hydrocarbons may be employed for this purpose; but I have found 7 process.

It is 'well known that the hydrocarbons just 5 5 i mentioned when combined with rubber react;

[upon the latter in avery peculiar 1 manner, 1

causing one element of the rubber to be prac .tically completely dissolved, while another element of the rubber resists thisdi'ssolving action and merely swells up and increases its bulk as the result of the distention ofits cells and minute canalsor passages by the hydrocarbon drawn thereinto by capillary action.

' The dissolved element-of the rubber when the operation is properly performed leaves cells of considerable size in the rubber compound which correspond to the cells formed by the mechanically-acting particles of rock saltYin the processdes'cribed in my said prior appli- 7o cation, while the smallcells formed bythe distention of the minute natural cellsand pas sages of the rubber correspond tothe cells formed by the chemicallyacting blowing agent or bicarbonate of soda in, said prior.

Thus bycombining with the rubher or sulfurized rubber a suitable hydrocarbon, such as paraffin, and subjecting this compound to heat upto the point of vulcanization large cells may be formed by the physical 8d solution of one element of the rubber and small cells formedabycapillary absorption of the hydrocarbon and; by the blowing of the l mass'by the gas or gases liberated by the subsequent thermochemical action,'all of these cells being set when the compound is vulcanized.

\ In carrying out mypresen't process I usually-make use of a rubber compound formed by mixing with crude rubber sufficientsulfur 0 to vulcanize the rubber, after which the by: droca-rbon, such as melted paraffin, is incorporated with the sulfurized rubber, the mass being then thoroughly mixed by running it through the rollers of an open mill. Either before or during the passage of the mass through such rollers 1 may mix therewith sufficient water to fill the minute cells and passages of the natural rubber when absorbed by such capillary cells and passages, the watoo bythese cells and passages, while the paraffin,

which is absorbed somewhat slowly, is exerting its dissolving action upon the more soluble portions of the rubber. When the rubber and the paraflin, with or without water, are thoroughly mixed by the rollers of the mill, the resultant mass is partially dissolved and partially undissolved, the capillary cells and passages of the undissolved portions being, however, distended by the absorbed liquid. Material so treated should then be heated to a temperature sufficient to liberate the gases for forming other cells, especially in the dissolved portions of the mass. The nature of the reaction that takes place is complex; but sulfureted hydrogen and probably other gases are liberated and form in the dissolved portions of the rubber innumerable other cells, which still further break up the solid mass to form a structure honeycombed with large and small cells and spaces. WVhen the heat is continued to the point of vulcanization, the vulcanizing action serves to mold the walls of allot the openings around the liquid and gaseous contents thereof into permanent elastic form, the product being an open porous irregular structure having a large number of small to minute cells and passages for receiving water and circulating it therethrough and at the same time having a sufiicient number of large openings to honeycomb the structure and leave only thin elastic fibers and connecting portions filled with cells, canals, and larger openings which break up these fibers and connecting portions still further. Hence no long fibers or groups of fibers remain in the interior of the rubber sponge and no long solid masses, all of these fibers and masses being broken up at many points in theirlengths, but in an irregular manner, and being elastic in every direction and therefore compressible into a small space, all of these parts returning to their own original positions by their elasticity when the compressing force is removed. Moreover, the small cells, the canals, and the large openings form a network of communicating openings and channels all capable of absorbing Water in exactly the same manner as a natural sponge and retaining the water unless the product issqueezed. A sponge substitute formed in this manner possesses substantially all of the characteristics of a natural sponge, is elastic and absorbent to the same extent, is much cheaper than thenatural sponge, and is very durable.

Having thus described my invention, I claim 1. The method of forming a sponge substitute, which consists in incorporating with rubber a sufiicient quantity of a chemicallyacting cell-forming solvent of rubber to only partially dissolve said rubber, and heating said compound to form cells therein and vulcanize the rubber.

2. The method of forming a sponge substitute, which consists in incorporating with rubber a suflicient quantity of a chemicallyacting cell-forming hydrocarbon to only partially dissolve said rubber, and heating said compound to form cells therein and vulcanize the rubber.

3. The method of forming a sponge substitute, which consists in incorporating with rubber a sufiicient quantity of paraffin to partially dissolve said rubber, and heating said compound to form cells therein and vulcanize the rubber.

4. The method of forming asponge substitute, which consists in incorporating with a sulfurized rubber compound a sufficient quantity of a chemically-acting cell-forming hydrocarbon to partially dissolve said rubber, and heating said compound to form cells therein and vulcanize the rubber.

5. The method of forming asponge substitute, which consists in incorporating with "a sulfurized rubber compound a sufficient quantity of a chemically-acting cell-forming hydrocarbon to partially dissolve said rubber, adding a suflicient quantity of water or other liquid to distend the cells of such rubber, and heating said compound to form other cells therein and vulcanize the rubber.

(5. The method of forming a sponge substitute, which consists in incorporating paraflin with rubber, and heating said compound to form cells therein and vulcanize the rubber.

7. The method of forming a sponge substitute, which consists in incorporating parafiin and water or other moistening ingredient with rubber, and heating said compound to form cells therein and "ulcanize the rubber.

8. The method of forming a sponge substitute, which consists in incorporating with sulfurized rubber a hydrocarbon capable of partially dissolving said rubber and causing a distention of the remainder, and then heating said compound to form cells therein and vulcanize the rubber.

In testimony whereof I have signed my name to this specification, in the presence of two subscribing witnesses, this 29th day of 

